AlmaLinux has issued an important security update for Thunderbird on version 10 of its operating system. The patch addresses a long list of vulnerabilities that could allow attackers to exploit memory safety flaws or escalate privileges within the browser and email client. These issues range from incorrect boundary conditions in networking components to dangerous use after free errors that might leak sensitive information or bypass security mitigations. System administrators should install the updated packages as soon as possible to keep their mail clients secure and prevent potential exploitation.

ALSA-2026:12285: thunderbird security update (Important)

ALSA-2026:12285: thunderbird security update (Important)

Hi,

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AlmaLinux: 10
Type: Security
Severity: Important
Release date: 2026-05-03

Summary:

Mozilla Thunderbird is a standalone mail and newsgroup client.

Security Fix(es):

* firefox: thunderbird: Incorrect boundary conditions in the Libraries component in NSS (CVE-2026-6772)
* firefox: thunderbird: Use-after-free in the JavaScript Engine component (CVE-2026-6754)
* firefox: thunderbird: Spoofing issue in the DOM: Core & HTML component (CVE-2026-6762)
* firefox: thunderbird: Incorrect boundary conditions in the WebRTC component (CVE-2026-6752)
* firefox: thunderbird: Other issue in the Storage: IndexedDB component (CVE-2026-6770)
* firefox: thunderbird: Invalid pointer in the JavaScript: WebAssembly component (CVE-2026-6757)
* firefox: thunderbird: Other issue in the Libraries component in NSS (CVE-2026-6767)
* firefox: thunderbird: Memory safety bugs fixed in Firefox ESR 140.10, Thunderbird ESR 140.10, Firefox 150 and Thunderbird 150 (CVE-2026-6786)
* firefox: thunderbird: Incorrect boundary conditions in the WebRTC component (CVE-2026-6753)
* firefox: thunderbird: Use-after-free in the Widget: Cocoa component (CVE-2026-6759)
* firefox: thunderbird: Use-after-free in the WebRTC component (CVE-2026-6747)
* firefox: thunderbird: Information disclosure due to uninitialized memory in the Graphics: Canvas2D component (CVE-2026-6749)
* firefox: thunderbird: Incorrect boundary conditions in the Libraries component in NSS (CVE-2026-6766)
* firefox: thunderbird: Privilege escalation in the Networking component (CVE-2026-6761)
* firefox: thunderbird: Mitigation bypass in the File Handling component (CVE-2026-6763)
* firefox: thunderbird: Privilege escalation in the Graphics: WebRender component (CVE-2026-6750)
* firefox: thunderbird: Uninitialized memory in the Audio/Video: Web Codecs component (CVE-2026-6748)
* firefox: thunderbird: Memory safety bugs fixed in Firefox ESR 115.35, Firefox ESR 140.10, Thunderbird ESR 140.10, Firefox 150 and Thunderbird 150 (CVE-2026-6785)
* firefox: thunderbird: Mitigation bypass in the DOM: Security component (CVE-2026-6771)
* firefox: thunderbird: Incorrect boundary conditions in the DOM: Device Interfaces component (CVE-2026-6764)
* firefox: thunderbird: Information disclosure in the Form Autofill component (CVE-2026-6765)
* firefox: thunderbird: Privilege escalation in the Debugger component (CVE-2026-6769)
* firefox: thunderbird: Uninitialized memory in the Audio/Video: Web Codecs component (CVE-2026-6751)
* firefox: thunderbird: Incorrect boundary conditions in the WebRTC: Networking component (CVE-2026-6776)
* firefox: thunderbird: Use-after-free in the DOM: Core & HTML component (CVE-2026-6746)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Full details, updated packages, references, and other related information: https://errata.almalinux.org/10/ALSA-2026-12285.html

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Kind regards,
AlmaLinux Team